Testosterone Administration Moderates Effect of Social Environment on Trust in Women Depending on Second-to-Fourth Digit Ratio.

Vincent Buskens,Jack Van Honk,Nynke Van Miltenburg,Werner Raub,Estrella R Montoya

doi:10.1038/srep27655

Vincent Buskens, Jack Van Honk + Show 3 more

Open Access

https://doi.org/10.1038/srep27655

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Abstract

Animal research has established that effects of hormones on social behaviour depend on characteristics of both individual and environment. Insight from research on humans into this interdependence is limited, though. Specifically, hardly any prior testosterone experiments in humans scrutinized the interdependency of testosterone with the social environment. Nonetheless, recent testosterone administration studies in humans repeatedly show that a proxy for individuals’ prenatal testosterone-to-estradiol ratio, second-to-fourth digit-ratio (2D:4D ratio), influences effects of testosterone administration on human social behaviour. Here, we systematically vary the characteristics of the social environment and show that, depending on prenatal sex hormone priming, testosterone administration in women moderates the effect of the social environment on trust. We use the economic trust game and compare one-shot games modelling trust problems in relations between strangers with repeated games modelling trust problems in ongoing relations between partners. As expected, subjects are more trustful in repeated than in one-shot games. In subjects prenatally relatively highly primed by testosterone, however, this effect disappears after testosterone administration. We argue that impairments in cognitive empathy may reduce the repeated game effect on trust after testosterone administration in subjects with relatively high prenatal testosterone exposure and propose a neurobiological explanation for this effect.

Highlights

Should be related to aggression, while in social environments in which dominance and status derive from other and non-aggressive behaviours, the relation between testosterone levels and aggression should disappear
Since effects of testosterone administration on cognitive empathy seem to depend on priming through prenatal testosterone, we included effects of 2D:4D ratio in the analyses. 2D:4D ratio has been established as an individual marker for differences in prenatal testosterone-to-estradiol ratio6. 2D:4D ratio was measured from a scan of the right hand of the subjects, a valid method to measure finger lengths[30]
The significant interaction effects imply that there is a positive effect on investments from being in the repeated game compared to the one-shot game in the placebo condition

Summary

Introduction

Should be related to aggression, while in social environments in which dominance and status derive from other and non-aggressive behaviours, the relation between testosterone levels and aggression should disappear. The trustee has an incentive not to share and in that case the investor is worse off after investing than in the case of not investing at all Due to these features, the trust game is an experimental paradigm for studying both trustfulness, indicated by investments, and trustworthiness, indicated by sharing through back transfers. Trust in the repeated game based on conditional behaviour of the investor and reputation building of the trustee presupposes that both subjects anticipate on each other’s behaviour and requires cognitive empathy more so than in the one shot-game. Too, that our hypothesis is exclusively on testosterone effects moderating the difference in trust between one-shot and repeated games rather than testosterone effects on baseline levels of investments in one-shot or repeated games For such hypotheses, we would need data about investors’ and trustees’ beliefs on behaviour of others (see Supplementary Information, Section 5)

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